Itinerant ferromagnetism in van der Waals 
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 crystals above room temperature

Zhang, Hongrui; Chen, Rui; Zhai, Kun; Chen, Xiang; Caretta, Lucas; Huang, Xiaoxi; Chopdekar, Rajesh V.; Cao, Jinhua; Sun, J. R.; Yao, Jie; Birgeneau, R. J.; Ramesh, R.

doi:10.1103/physrevb.102.064417

Cited by 87 publications

(76 citation statements)

References 37 publications

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“…The X‐ray diffraction experiment indicates that Fe(1)‐Ge split‐site pairs can form ordering, [ 14 ] while such ordering was not considered in other recent works. [ 17,20 ] Further atomistic microscopy study is still necessary to confirm these structural details of Fe 5 GeTe 2 . Figure a shows the possible split‐sites of Fe(1) (Fe(1) up , Fe(1) down ) and Ge (Ge up , Ge down ) marked by pink and blue open circles, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…As a promising vdW ferromagnet, the Fe n GeTe 2 family ( n = 3, 4, 5) was recently proposed based on its high T C (260–310 K) and large saturation magnetization. [ 12–19 ] In particular, Fe 5 GeTe 2 with a rhombohedral space group (R

\overset{3}{true}

m) is expected to show the highest T C among Fe n GeTe 2 family because the additional Fe layer in Fe 5 GeTe 2 can boost magnetic interaction. [ 15,16 ] Also, the additional Fe layer gives rise to three magnetic transitions depending on temperature (around 70, 180, and 270 K) for in‐plane ( ab plane) magnetization, which have not been reported in Fe 3 GeTe 2 and Fe 4 GeTe 2 crystals.…”

Section: Introductionmentioning

confidence: 99%

“…[ 15,16 ] Also, the additional Fe layer gives rise to three magnetic transitions depending on temperature (around 70, 180, and 270 K) for in‐plane ( ab plane) magnetization, which have not been reported in Fe 3 GeTe 2 and Fe 4 GeTe 2 crystals. [ 12,15–17 ] Recently, these unconventional magnetic properties have been explained with magnetic anisotropy or/and spin reorientation by the Fe atoms in Fe 5 GeTe 2 . [ 14,16,17 ] However, the exact mechanism of such non‐trivial magnetic behaviors is still unclear because it is also involved with the structural complexity in Fe 5 GeTe 2 .…”

Section: Introductionmentioning

confidence: 99%

“…[ 12,15–17 ] Recently, these unconventional magnetic properties have been explained with magnetic anisotropy or/and spin reorientation by the Fe atoms in Fe 5 GeTe 2 . [ 14,16,17 ] However, the exact mechanism of such non‐trivial magnetic behaviors is still unclear because it is also involved with the structural complexity in Fe 5 GeTe 2 . For instance, May et al.…”

Section: Introductionmentioning

confidence: 99%

“…reported that Fe 5 GeTe 2 has ordering driven by Fe and Ge positions, [ 14 ] while the ordering of Fe and Ge pair was not considered in other works. [ 17,20 ] It is very important to clarify these structural details because they may have significant effects on the magnetic ordering in Fe 5 GeTe 2 . Therefore, systematic study for finding the correlation between such non‐trivial magnetic behaviors and the atomistic structure of Fe 5 GeTe 2 is needed to realize room temperature spintronic devices with this new vdW ferromagnet.…”

Section: Introductionmentioning

confidence: 99%

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Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Park

Kim

et al. 2021

Adv Funct Materials

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Microscopic structures and magnetic properties are investigated for Fe5−xGeTe2 single crystal, recently discovered as a promising van der Waals (vdW) ferromagnet. An Fe atom (Fe(1)) located in the outermost Fe5Ge sublayer has two possible split‐sites which are either above or below the Ge atom. Scanning tunneling microscopy shows √3 × √3 superstructures which are attributed to the ordering of Fe(1) layer. The √3 × √3 superstructures have two different phases due to the symmetry of Fe(1) ordering. Intriguingly, the observed √3 × √3 ordering breaks the inversion symmetry of crystal, resulting in substantial antisymmetric exchange interaction. The temperature dependence of magnetization reveals a sharp magnetic anomaly suggesting helical magnetism of the Fe5−xGeTe2 due to its non‐centrosymmetricity. Analytical study also supports that the observed ordering can give rise to the helimagnetism. The work will provide essential information to understand the complex magnetic properties and the origin of the new vdW ferromagnet, Fe5−xGeTe2 for future topology‐based spin devices.

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Section: Resultsmentioning

confidence: 99%

\overset{3}{true}

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Park

Kim

et al. 2021

Adv Funct Materials

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Disentangling the Unusual Magnetic Anisotropy of the Near‐Room‐Temperature Ferromagnet Fe₄GeTe₂

Pal,

Abraham,

Mistonov

et al. 2024

Adv Funct Materials

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In the quest for 2D conducting materials with high ferromagnetic ordering temperature the new family of the layered FenGeTe2 compounds, especially the near‐room‐temperature ferromagnet Fe4GeTe2, receives a significant attention. Fe4GeTe2 features a peculiar spin reorientation transition at TSR ≈ 110 K suggesting a non‐trivial temperature evolution of the magnetic anisotropy (MA)—one of the main contributors to the stabilization of the magnetic order in the low‐dimensional systems. An electron spin resonance (ESR) spectroscopic study reported here provides quantitative insights into the unusual magnetic anisotropy of Fe4GeTe2. At high temperatures the total MA is mostly given by the demagnetization effect with a small contribution of the counteracting intrinsic magnetic anisotropy of an easy‐axis type, whose growth below a characteristic temperature Tshape ≈ 150 K renders the sample seemingly isotropic at TSR. Below one further temperature Td ≈ 50 K the intrinsic MA becomes even more complex. Importantly, all the characteristic temperatures found in the ESR experiment match those observed in transport measurements, suggesting an inherent coupling between magnetic and electronic degrees of freedom in Fe4GeTe2. This finding together with the observed signatures of the intrinsic two‐dimensionality should facilitate optimization routes for the use of Fe4GeTe2 in the magneto‐electronic devices, potentially even in the monolayer limit.

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Magnetic Anisotropy Control with Curie Temperature above 400 K in a van der Waals Ferromagnet for Spintronic Device

Tang

Huang

et al. 2022

Advanced Materials

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The technological appeal of van der Waals ferromagnetic materials is the ability to control magnetism under external fields with desired thickness toward novel spintronic applications. For practically useful devices, ferromagnetism above room temperature or tunable magnetic anisotropy is highly demanded but remains challenging. To date, only a few layered materials exhibit unambiguous ferromagnetic ordering at room temperature via gating techniques or interface engineering. Here, it is demonstrated that the magnetic anisotropy control and dramatic modulation of Curie temperature (Tc) up to 400 K are realized in layered Fe5GeTe2 via the high‐pressure diamond‐anvil‐cell technique. Magnetic phases manifesting with in‐plane anisotropic, out‐of‐plane anisotropic and nearly isotropic magnetic states can be tuned in a controllable way, depicted by the phase diagram with a maximum Tc up to 360 K. Remarkably, the Tc can be gradually enhanced to above 400 K owing to the Fermi surface evolution during a pressure loading–deloading process. Such an observation sheds light on the understanding and control of emergent magnetic states in practical spintronic applications.

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Itinerant ferromagnetism in van der Waals Fe5−xGeTe2 crystals above room temperature

Cited by 87 publications

References 37 publications

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Disentangling the Unusual Magnetic Anisotropy of the Near‐Room‐Temperature Ferromagnet Fe₄GeTe₂

Magnetic Anisotropy Control with Curie Temperature above 400 K in a van der Waals Ferromagnet for Spintronic Device

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Itinerant ferromagnetism in van der Waals Fe5−xGeTe2 crystals above room temperature

Cited by 87 publications

References 37 publications

Direct Observation of Fe‐Ge Ordering in Fe5−xGeTe2 Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe5−xGeTe2 Crystals and Resultant Helimagnetism

Disentangling the Unusual Magnetic Anisotropy of the Near‐Room‐Temperature Ferromagnet Fe4GeTe2

Magnetic Anisotropy Control with Curie Temperature above 400 K in a van der Waals Ferromagnet for Spintronic Device

Contact Info

Product

Resources

About

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Disentangling the Unusual Magnetic Anisotropy of the Near‐Room‐Temperature Ferromagnet Fe₄GeTe₂